1. Field of the Invention
The present invention relates to the field of computers. More specifically, the present invention relates to computer architecture.
2. Description of the Related Art
In general, branch predicting utilizes branch prediction history and prior branch resolutions. As branch predictions are generated, they are shifted into a branch history register. In various branch prediction schemes, program counters are hashed together with the branch history to select a branch prediction for a branch-type instruction from a branch prediction table. In addition, another branch prediction technique utilizes multiple instances of branch prediction tables. Each of the branch prediction tables are maintained in accordance with a different branch prediction algorithm. A branch prediction for a single branch-type instruction is selected from the different instances of branch prediction tables and combined into a single branch prediction for the branch-type instruction.
Unfortunately, speculative execution and reliability of branch prediction suffers because branch history does not include history for recent branch-type instructions. As the window of unavailable recent branch predictions grows, then the reliability of branch predictions decreases.. In addition, predicting for a single branch-type instruction is insufficient to meet the demands of high performance processing environments. High performance processing environment face challenges in overcoming the inadequacy of single branch prediction, and in coordinating branch prediction to make recent branch predictions available as a factor in current branch predictions. Accordingly, a branch prediction technique is desired that satisfies the demands of a high performance processing environment.